If you would like to change the email address associated with your account, you can do so directly from your account page at https://airtable.com/account.
From your account page, click the "Edit email" option next to where your email address is shown.
To confirm a change to your email address, you'll need to enter your current password and the new email address.
If you signed up for Airtable with a Google login, you will not be able to edit the email associated with your account unless you add an Airtable-specific password to your email (separate from the password associated with your Google login). Clicking the "Edit email" option will bring up a prompt for you to add an Airtable password, then send a password creation link to your Gmail inbox.